Semiautomatic telephone system



May 2, 1933. F. GOHOREL SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. ll 1931 5 Sheets-Sheet 1 hut-E1 Inuenlu'r' Farr-land Gm May 2, 19133. F. GOHOREL 1,907,062

SEMIAUTOMATIC TELEPHONE SYSTEM 3 Sheets-Sheet 2 Filed Sept. 11, 1931 May 2, 1933. I F. GOHOREL SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. 11, 1951 5 Sheets-Sheet 5 ink N R a .3, 22:2: :2 EmNQvQE NW SIJIIUF finru T a 53f & 225: n: N I l l l w Q m a Q n w L Q I EIL E R a a w N3 Jr N \Q fi Gm N. I 1 PH Q N P1 R s i 3 Tfiizss: 2: v n m 3:22:53: 1|] zznni: m m v lllllll W 3 Patented May 2, 1933 UNITED STATS ATENT @FFl FERNAND GOHOREL, OF PARIS, FRANCE, .ASSIGNOR, BY IVIESNE ASSIGNMENTS, TO

ASSOCIATED.ELECTRIC LABORATORIES, INC., OF CHICAGO,

'IION DELAWARE ILLINOIS, A GORPORA- SEMIAUTOMATIC TELEPHONE SYSTEM Application filed September 11, 1931, Serial 1 The present invention relates to semi-automatic telephone systems in which communications between two subscribers are established at a distance, by manual operators.

The said invention is more particularly applicable to telephone networks called rural networks in which the subscribers are grouped in small capacity ofiices connected either among themselves or to central manual ofices of more importance.

In general, the great number of these offices and the small number of circuits which connect them render the necessary operations complicated for establishing communications in these networks. This augments chances of wrong connections and the time required for putting these connections through. v

The present invention has for its object to remedy these inconveniences by suitable means, rendering always simple the operations carried out by the operator for esta lishing these communications at a distance, and this no matter how many and how disposed are these oifices in question. The choice of connecting circuits to connect u whichever two subscribers attached to this otfice of the same group or attached to the same oflice is effected solely bythe sending of impulse trains corresponding to the sub scribers numbers.

A rural network can be considered as comprising a first olfice connected by a plu rality of junctions to a more important ofiice served by the manual operator. Also, other oflices connected each one by a junction to the first olfice these said ofiices being able in their turn to serve more distant ofiices to which they are-connected by a junztion and so on.

In the following, by tandem otfice is meant'an ofiice which serves other oifices more distant than itself from the central manual oflice, and by central terminus office is meant one which is not connected to any ofiice more distant than itself from the central manual ofiice.

One of the features of the invention consists in the first arrangement of switches more particularly applicable to the case of 0. 562,241, and in France September 19, 1930.

an ofiice tandem and which is such that for each junction at the preceding otfice (with regard to the manual op'erators position) three switches are provided to connect the said junction (which is called the principal junction) to subscribers or to the junctions going towards the more distant oflice. The first of these switches (X) is used either for finding a calling line'and connecting it to the corresponding main junction, or for rotating it on to the called line through the action of impulses sent by the manual operator over the main junction, eventually to connect the calling subscriber or called subscriber, or for rotating it onto the main junction or to a second switch described hereafter.

The second of these switches (Y) is used for rotating onto a called line under the effect of impulses sent by the manual op erator over the main junction and for connecting the subscriber thus called to the subscriber already connected to the first switch, eventually to permit establishment of a localcommunication circuit between the two subscribers. 'When the first of the two switches is used for a connection between two subscribers of the same network the third of these switches (Z) is used for either finding a calling line or finding a called line through the action of impulses sent by the manual operator over the main junction, eventuallyto connect a calling or called subscriber to the main junction.

The invention is also applicable to cases where there are a plurality of groups of switches X and Y and a switch Z for each main junction. The groups of switches X and Y being used one after another in the case where there are several simultaneous inward connections passing through the of fice in question, switch Z being used for connections with the preceding otfice when all the groups X and Y are engaged upon inward connections.

Another feature of the invention consists in a second simple arrangement of switches in combination with olfices having the first arrangement. This is more particularly applicable to terminus oifices from whence it.

will be noticed that in general a number of inward connections is very small which permits maintaining the junction occupied during the said inward connections without resulting in an appreciable reduction in efficiency of the junction.

To this end, the second arrangement is constituted by the association of two switches with the junction going to the preceding otlices, the first switch X analogous to the switch X described above, a second switch Y analogous to switch Y described above.

Another feature of the invention resides in an arrangement of electric circuits permitting'the'starting oil in the operation of switch Y described above only it the preliminary setting of switch X does not correspond to the digit which is to set switch Y.-

The object of this arrangement is to set in operation the arrangement constituted by a group of switches X and Y which is destined to establish inward communications only in ofiices wherethey must be used.

Another feature of the invention consists in special means for keeping in abeyance calls initiated by subscribers while permitting the operator to put through other calls, the operator replying to the subscribers calls only at her own wish.

One of the most important devices in the invention for attaining this object consists in the using of one of the two wires of the junction for the transmission of impulses and signals and the other wire for the control of different operations for effecting signaling, supervision. release, etc.; this control being obtained by a I polarized relay branched on the last-mentioned wire and operated at a distance in one direction or the other by the act-ion of the manual operator.

A feature of the invention consists also in the arrangement of a circuit for operating the called sub'scribers bell which consists in the calling generator of the manual office, one wire of the junction, the bell of the called subscriber, and earth, at the attached oiiice considered, the other wire of the junction being used for maintaining the switches used in the connection in operative condition.

The invention is also characterized by the circuit for testing the impulse circuit, and which includes the sending wire and a relay at the manual office, whose energization pre-. vents the sending of impulses in such a man ner as to avoid this sending and signal the operator of it as long as'the switch which should be controlled by the impulse at the rural office is not free, oris not in a position to permit it to reply to these impulses.

The annexed drawings represent by way of example one method of putting the invention into operation. I 7

Fig. 1 shows a schematic example of a simple network.

Fig. 2 shows a detailed scheme of the manual operators position.

Fig. 3 shows a detailed scheme of the tandem ot'rice.

Fig. 4 shows a detailed scheme of a terminus oiiice.

Fig. 5 shows a dialing cord.

Fig. 6 shows a part of a regular cord circuit.

In the following the description is devoted to the case Where there is a tandem oflice attached to a manual ofiice, and a terminus oiiice attached to a tandem office. The invention is not, however, limited to the case of a single tandem oilice, but is applicable also to the case of a plurality of connected tandem ofiices.

In Fig. 3 switch R1 represents switch X.

In Fig. 3 switch R2 represents switch Y In Fig. 3 switch R3 represents switch Z.

In Fig. 4 switch RC1 represents switch X.

In Fig. 4 switch RC2 represents switch Y.

Each subscribers line or junction from the oitice in question is equipped inside the office with a cut-off C and a calling relay A and is multipled on the banks of the connectors. In addition, the office connected directly to the manual position (perhaps equipped for one or more junctions with the said position) has each of its circuits supplied at each end with an equipment as represented in Figs. 2 andS.

In these main lines the operation is as follows:

Manual 0 7m call by a rural subscriber (a) The case of an office directly connected to the manual position.

"he subscriber operates his magneto and energizes its calling line relay A which causes the sending of a calling signal over one of the junctions (if they are free) to the manual position. The calling lamp associated with the junction in question lights.

The operator replies by inserting the plug of a cord in the jack RP corresponding to the said junction which causes by the sending of a suitable potential between one of the wires and earth and also through the medium of a polarized relay the setting in operation of a switch R1 (Z) (connector finder), or R3 (Z) if the local connector Rl-R2 (X-Y) is occupied until it finds the calling line upon which it stops. At this time the calling signal is removed, and through this the call is automatically cut off at the manual position.

In addition, immediately upon plugging in the supervisory lamp flickers during the entire hunting period. It assumes a steady glow during the calling period. It is extinguished immediately upon the reply of the calling subscriber.

In the case where no circuit is free at the moment of the subscribers call, his call remains in abeyance 011 relay A. This call is transmitted as soon as a circuit becomes available. During the entire period between the reception of the call on relay A and the taking of the line by the finder an occupation tone is sent to the subscriber notifying him that his call is registered.

(b) Case of connected terminus office.

The general operation is identical with that described above and only differs in the following points: 1

The subscriber operates his magneto and through the operation of his relay A (Fig. 4), for example, causes the sending of a calling signal over the junction from the oihce in question to the office to which it is attached. In this latter oflice, this signal causes the energization of a calling relay A of the junction concerned (Fig. 8). This call is then carried out in the same fashion as previously described. It is extended via the different connected ofiices until it arrives at the manual position.

The operations involved in the reply are of the same kind as previously described, and the operations succeed one another in the oflice concerned, until the taking of the calling subscriber. At this time the call is automatically cut oil by the definitive suppression of the rural manual calling signal.

The communication over, the operator is notified by the lighting of the supervisory lamp, the lighting being caused by the hanging up of the. calling subscriber. The operator withdraws her plug. All the switches return to normal.

Rural subscriber called by the manual 077206 The operator inserts the plug of a cord in the calling jack which causes the sending between one of the wires and earth of a potential such that the polarized relay of the rural oflice is energized in a sense opposite to that used for the reply to the call, as described above. By this means the switches of the oifice in question are set in condition for reception of the dialling the same as if the said'ofiice is in calling condition, in which case the rural manual calling signal is. immediately suppressed and postponed pending the release of the circuit in question.

Through the medium of associated relays the putting in this position of the polarized relay permits also the using of the other position (initial Y used for the finding of a call as has been seen above) for the realization of another operating condition as described in the following and thus until the release of the circuit by the operator. The latter inserts in an associated dialling jack of the circuit in question the plug of her calling dial. A dialling lamp associated with the said dial is immediately caused to flicker until the switches of the otfice concerned are in the dialling position, which causes by the sending from the rural office of a suitable signal the extinction of the said lamp.

The operator impulse train.

To this end, she winds up the dial and through this operation the energization current of the polarized relay is reversed and also the position of the said relay used for establishing different impulsing circuits. The impulses are sent and registered on a switch X1 of control RA, Fig. 3. This causes the movement of switch Rl' (X) or R3 (Z) if Rl-R2 (X1) are occupied folowing upon the digit sent (characteristic of the office to be reached) (a) To select a subscriber if he is attached to this oflice. In this case control switch A moves automatically into the position for receiving the following digit.

(b) To select a junction corresponding to the chosen ofiice which causes if the said ofiice is not engaged the connection of the position via a tandem office. The switches of the tandem ofiice are put out of circuit upon the reply 01'. the called subscriber.

he operations then succeed one another at the terminus ofice (Fig. 4) in the same manner as described above for the tandem oflice. In both cases at the manual position can then send'her first oflice or the terminus otlice are in position to receive the following impulse train. This operation is repeated in an identical manner for the two 'ollowing impulse trains corresponding to the tens and units digits. is arrangement allows of maximum reliability of operation.

In addition, and in spite of this signal, if the operator winds up her dial too soon,

diately rendered inoperative. At the end of the last impulse train counted by switch associated with the equipment of the circuit (manual position, Fig. 2) the calling current is automatically cut 0H. If the subscriber is busy a signal sent immediately by the taken rural position prevents off of this call and the supervisory lamp of the cord in question is set flashing, thus notifying the operator. The subscriber being free, the supervisory lamp is lit with a steady glow during the entire period of the cal. The unhooking by a called subscriber causes the suppression of the call and the extinction of the supervisory lamp. In addition, upon the sending of the first digit corresponding to an engaged connected the cutting ofli ce, the dialling lamp remains flashing, so notifying the operator.

Upon the hanging up, the subscribers supervisory lamp lights and the operator withdraws her plug. By this operation and through the medium of polarizedrelays returning to their middle positions, the switches of the ofiice in question return to normal.

Local connections These connections can be established between subscribers of the same network.

(a) Upon a call of a calling subscriber:

These operations having been carried out as indicated in the corresponding paragraph, the operator without removing her answering plug introduces her dialling plug into the corresponding jack. By this operation the switches of the oflice concerned are set in the dialling position, as in the same proceeding described above (call by a manual exchange). It suflices then to send the number of the called subscriber.

Sending of the first digit received solely on the control switch RA, Fig. 3, of the tandem office directly connected causes the rotation of switch R2 (Y), Fig. 3, either to select a junction or to select a subscriber of the said office. In the case where the digit received on the control switch RA (Fig. 3) corresponds to a circuit occupied by the connector R1 (X) which is associated with it, the connector R2 (Y) isnot set in use and the connection (impulse supervision) with the said circuit is established as at the beginning by switch R1 The following impulses received at the terminus position causes the rotation of connector RC2 (Y) from the said position, (Fig. 4), the supervision being the same as that described above for the dialling of a first subscriber. At the end of the third impulse train the call to the called subscriber is cut off (if he is free) until his unhooking which causes the extinction of the supervisory lamp. The operator can enter upon the conversation and can withdraw her plug immediately upon the establishment of the connection between the two subscribers. The connectors R1, R2 or R01, R02 are maintained in busy condition in the office where they are used and maintained if there are any and through their medium the connectors R1 or RG1 from beyond. The switches not mentioned above are returned to normal.

Upon the hanging up of either of the subscribers the switches held in the connection are freed.

(b) Local connections can be established by successive dialling of two subscribers. The first subscriber is called as described in paragraph Rural subscriber called by the manual exchange. This first subscriber having replied, it is sufficient without any further operations to dial the number of the second subscriber, the operations at this time being identical to those described above. Special operations (1) Supervision and release of local connections by the operator.

She can, after unplugging and when any of the inlets to the local connector are free, enter into the conversation. In order to do this she plugs in on the calling side, winds up her dial, and does the following:

a) In the case where the local connector X, Y is that of a terminus office, she dials the special number for this office. The connector X or Z at the tandem office thus chooses the circuit going to the found group X, Y and the connection is established between the operator and the two conversing subscribers.

(b) In the case where the local connector X- Y is that of a tandem oiiice, she dials a number which is special for this operation. Switch Z of this office is then switched into a position which connects the circuit to the group X Y and the conversation between the operator and the two subscribers takes place.

Under these circumstances the operator can free the local connection by pressing a special key, individual to the position and called the forced listening and releasing key. This operation reverses the energization current of the polarized relay of the ofiice concerned. The latter by a group of relays which are associated with it'at this moment causes the release of a relay which itself brings about the release of the connection.

(2) Verification of the nature of the busy connections met with means of superlistening to established communications is done directly through the medium of the ordinary listening key only when these connections are established by the local connector at a terminus office. In all other cases the operator has to use her forced listening key. This operation reverses the energization current of the polarized relay of the tandem office which by a group of relays which are associated with it at this moment completes the connection of the circuit with the occupied portion reached by the switches X or Z of this office.

The following is a detailed circuit description.

I These are signalled by visory lamps. In general,

I. Gall by a rural subscribe r In the following description T denotes an operated contact and R a normal contact.

First case: The subscriber is attached to a tandem ofi'ice, Fig. 3, the said subscriber operates his magneto and energizes relay A overthe circuit: magneto, lower line, upper winding of relay A, RG1, upper line, normal contacts of switch hook to the other pole of the magneto. A holds up from battery through the lower winding of A, TAl, RC2, relay P, to earth.

The latter relay energizes and at TPl sends an earth to relay 9 of one or the other of the idle circuits, the circuit being from R21, lower winding of relay 9, to battery. A busy relay opens this circuit at contact 21.

In addition, at TF2 relay 0 is operated in a vibrating circuit through the medium of its contact 01, the interruptions of the current in the lower winding of said relay produce in the upper winding an alternating current of musical frequency, which is superimposed upon the holding circuit of relay A through the upper winding of relay 0, coupling condenser C9, RC2, TAl, lower winding of relay A. By induction between the two windin s of relay A, this current is sent on to the calling subscriber. If the latter takes 01? his receiver he hears the signal of occupation notifying him that his call is registered but is in abeyance.

If a circuit is free and by the energization of relay 9 as seen above, the calling signal is sent to the manual position over the circuit: battery, upper winding of retard S1, T91,'R132, R41, upper wire of the junction circuit connected to the manual position.

At the manual position, Fig. 2, the circuit continues by upper wire of the junction R11, R41, upper left-hand winding of the trans former, winding of relay 5, and earth which energizes relay 5 and lights the calling lamp associated with the junction over the circuit: earth, T52, H (normal position of the counting switch RC) and battery through the calling lamp LA. Relay 3 is energizedover the circuit T52 and battery through the winding of said relay. The operator replies by inserting a plug of a cord in the answering jack. I

Relay 8 operates by battery through the supervisory lamp LS, sleeve 1 of the plug and the answering jack, R105, upper winding of relay 8, to earth. 0

Relay 6 operates over the circuit: battery, through its upper winding, T81, and earth.

Relay 1.0 operates from earth, R23, upper winding of 10, H1 (normal position of RC) T62 and battery, through supervisory lamp LS. This lamp lights in series with the upper winding of relay 10.

The energization of relay 10 causes:

(a) At T101 a holding up of relay 8 from earth, T101, T83, lower winding of relay 8, R43, R71, and battery, through the safety resistance (6) Upper winding of said relay is put out of circuit by the opening of contacts 105.

(0) At T106 contact H1 is short circuited.

(cl) T102 the rotation circuit of the counting switch is completed over the circuit: battery, winding of motor magnet RC, T102, home contact of the bank 0, wiper W, normal contact of the motor magnet RC1 and earth. The latter operates by self-interruption, and leaves its initial position and comes to position 1, where we get the following circuit: battery, winding of the motor magnet RC, T102, wiper TV, contacts 1, 2, 3 of bank C in parallel, T82, RC1 and earth. The switch continues its hunting and stops in position 4.

((2) At T103 a circuit is closed for the lighting of the busy lamps LO corresponding to other positions.

(f) Finally at T104, battery (with positive earth return) is sent on the lower wire of the junction from positive through a safety resistance, T61, T104, winding of the retard S, lower left-hand winding of the transformer and lower line of the junction.

The calling lamp LA is extinguished by the opening of H (normal position of BC).

In addition upon the arrival at position 4 of the control switch We get the circuit: Interrupted earth, position 4 on the bank B, wiper 1V1, T51, upper winding of relay 2, and battery through the safety resistance.

The operation of relay 2 causes the periodic opening of contact 23 which periodically removes the short circuit from the lower winding of relay 10, during which time this relay maintains itself by its two windings in series, but the supervisory lamp LS flashes, advising the operator that hunting is set in operation at the rural position.

In Fig. 3, we have the circuit from battery on the lower wire of the junction, winding of polarized relay 15, to earth. This relay operates and closes its contacts 152 and 154. Relay 12 operates from battery, winding of relay 12, R61, T154, and eartl. Relay 2 operates through T152. This slow-to-release relay will remain held up during the movement of relay 15 from one operated position to the other.

The operation of relay 2 causes:

(1) At T23 the connecting of earth to the main hold wire and the operation of relay 27 by battery, winding of said relay R321, T23, and earth.

(2) At 21 the opening of the circuit of relay 9 which holds itself energized from earth T122, R103, and lower winding of said relay.

Through the operation of relay 12 we get battery through the safety resistance T124, R322, winding of relay 31, H2, H, and earth.

Relay 31 operates and holds up at T313.

Switch R1 starts to hunt from a circuit:

earth, RPl, R101, T121, T311, R262, motor magnet R1, through its interrupter. It operates by self-interruption to advance its wipers over the bank contacts where are arranged dilterent subscribers lines. The wipers arrive on the line of the calling subscriber.

We then get the circuit: earth, TA2, bank contact A, and wiper A1, switch R1, T313, T123, lower windingv of relay 10, battery.

The latter operates and opens at 101 the hunting circuit indicated above, causing thus the stopping of the finder switch B1 on the contacts corresponding to the calling subscriber- Relay 10 holds up from battery, upper winding of said relay T102, T23, and earth.

The circuit of relay 9 is opened at contact 103 which removes by the opening of contact 91 battery fromv the upper wire of the junction.

This causes at the manual position, Fig. 2, the release of relay 5 which opens at 51 the intermittent circuit of relay 2. At R23 the short circuiting of the lower winding of relay 10 lights the supervisory lamp LS with a steady glow which notifies the operator of the finding of the calling subscriber, itnd of the cut-off of the call as indicated he- The release of contact of relay 3 by the opening of 52 causes interrupted earth to extend from position 4: of bank A of the counting switch RC, Wiper 1V2, R31, and battery through the winding of relay 1, which operates and releases intermittently.

During the period of energization of the said relay, at T11 we get alternating current with an earth return sent over the upper wire of the junction. During its normal period we get at R11 the upper wire ofthe junction connected to relay 5, Fig. 2.

A condenser 01 allows the operator to assure herself by the operation of a listening key of the cut-off of the call. 7

In addition, a circuit is closed from earth R32, position at of bank'C, T102, wiper 1V, battery through the motor magnet R0, the latter energizes and remains operated until the opening of the said circuit.

At the rural position, Fig. 3:

During the period of sending of alternating current on the upper wire of the junction, a circuit is closed from the upper wire of junction R41, R132, R91, condenser C10, winding of alternating current relay 7 and earth.

Relay 8 operates from T71. The following circuit then closes: earth, T83, R131, T312, the windings of relay 26 in series, wiper T1 and bank contact T of the finder R1, and battery through the winding of relay C of the subscriber in question.

[The two relays C and 26 operate in series.

The latter holds up series with rela 0 over the circuit: battery, winding of relay C, T1, lower winding of relay 26, T261, T271, and earth.

The energization of relay C causes the release of associated relay A by the opening of C2 and the opening of C1 removes the connection between the upper line and relay A.

The calling circuit being thus completed, the circuit is closed from the upper wire 0 the junction, R41, T81, R141, R323, R291, T263, wiper and bank contact of the finder R1, upper wire of the subscribers line, switch hook, bell, condenser, lower wire of the subscribers line, bank contact and wiper of the finder R1, T265, R292, R324, R141, T82, and earth.

The calling subscribers bell is thus rung, notifying rim of the reply of the operator.

During the time the calling current is removed the release of relay 7 causes relay 8 to return to normal which places a battery via the circuit, retard S1, R142, R82, etc. This is-extended to the lower wire of the subscribers line. The upper wire is connected to earth through the winding of relay 9 over the circuit, R141, R81, upper winding of relay 9, H1 normal position of RA) and earth.

The above circuit is opened at the subscribers station by the interposition of a condenser in series with the subscribers bell, and will only be closed in series with the receiver and the secondary of the induction coil if the subscriber takes off his receiver. Theoperation reproduces itself periodically until the subscriber unhooks his receiver.

lVe then get by the operation of relay 9 as indicated-above the following circuit: battery, upper winding of the retard S1, T91, R132, R41, upper wire of the junction to the manual position (Fig. 2) R11, R41, transformer and relay 5 to earth.

By the operation of relay 5 we get:

(a) The operation of relay 3 via T52, which by the opening of 32 deenergizes the motor magnet RC (operated during the entire preceding period). The wipers move to position 5. The circuit of relay 1 is opened at 31, and also at contact l bank A.

(7)) Operation of relay 2 from earth, bank contact 5, of bank B, wiper 1V1, T51, upper winding of relay 2, and battery through the safety resistance.

The lower winding of relay 10 is again unshort circuited, the associated supervisory lamp LS of the cord going out.

The operator, notified of the answering of the subscriber, can listen in on the conversation by the operation of her listening kev.

The conversation currents are transmitted orer the two-line wires in series through (at the rural ofiice, Fig. 3) condensers Cl and C2.

The Conversation finished, the subscriber replaces his receiver which causes the opening of the holding circuit of relay 9 (Fig. 3) and the removal of battery placed on the upper wire of the junction. This at the manual position through the release of relays 5 and 2 causes the lighting of supervisory lamp LS.

The operator is notified of the hanging up or" the calling subscriber.

There is provided an arrangement for recalling the subscriber if necessary by the simple operation of a calling key.

The sending of alternating current from the cord in use causes the operation of re lay 9 through the condenser C2, closes the circuit: earth, T91, bank contact 5 of bank A, wiper V2, R31 and battery through relay 1. The latter energized sends via T11, alter nating current from earth to line as before. The operator repeats the operation of throwing the calling key until the subscriber by unhooking extinguishes the lamp LS.

In every case the operator, having received the finishing signal, releases the circuit by withdrawing the plug from the jack in question.

This operation causes the release of relays l0, 8, and 6. The counting switch RC returns to its initial position over the circuit: earth, interrupter RC1, bank D, wiper N3, R102, motor magnet of the said switch to battery.

At 103, the busy lamps corresponding to the circuits are extinguished.

At 104 positive battery is removed from the lower wire 01": the junction.

- By the return to its middle position of relay 15 (Fig. 3), We get:

Opening of contact 154. This releases relay 12 which at 124 deenergizes relay 31.

Opening of contact 152. This releases relay 2 which at 23 opens the circuit of relay 27 which by opening its contact 271 deenergizes relays 26 and C.

The following circuit is then closed: bat tery through the motor magnet of R1 via its interrupter, R262, R311, and earth through bank X1. The switch hunts until it reaches its home position. Everything is then normal.

Second case: The subscriber is attached to a terminal oflice (Fig. 4).

As indicated previously, the sending of calling current by the subscriber is received on relay A (upper winding) which holds up in series with relay P through winding of P, TA1, lower winding of A, RC3, andv earth. An occupation tone is sent over the calling subscribers line as in the previous system.

By the operation of P a circuit is closed from earth, TPl, R21, R132, lower winding of relay 9 to battery.

By the operation of relay 9 a circuit is closed through the retard S1, R42, T91, R63, and upper wire of the junction connection to the tandem office (Fig. 3) ROl, winding of calling relay A, to earth.

The operation of the said relay causes at TAl the operation of relay 9.

The calling signal is then re-transmitted to the manual position, and is treated in the same fashion as described in the previous paragraph. The operation is identical up to the time of setting R1 in operation.

The finder arriving on the position corresponding to the calling unction is stopped by the opening of contacts 101, due to the energization of relay 10 in the following circuit: earth. TA2, bank contact A, wiper A1, of the finder R1, T313, T123, lower winding of relay 10, and battery. The energization circuit of relay 5) is opened at 103, which causes the removal of battery from the upper wire of the junction.

The following circuit is also closed: earth, TA2, contact C, wiper C1 of the finder, T312, T104, lower winding of relay 14, to battery. This relay energizes and holds up from battery resistance R1, upper winding of saio relay T143, T23, and earth.

The circuit'is closed from earth, T143, R131, T312. both windings in series of relay 26, wiper T. bank contact T1, winding oi. relay C, to battery. These two relays energize in series and hold .up by lower winding of relay 26, T261, T271. and earth.

The 0; eration ot' relay C opens at (Y1 the circuit of the calling relay A Battery comes from the terminus position via the upper wire of the junction, and is sent to the manual position over the circuit: upper wire of the junction, bank contact and wiper +1, of the finder R1, T263, R291, R323. T141, R41, and upper wire of the junction going to the manual position.

The removal of the battery during the period between the operation of relay 1'0 and the deenergization of relay 9 and the holding up of relays .14 and 26 does not produce the cut-oif'of the call, the momentary release of relay 5 not having produced the deenergization of the slow-to-release relay 3, (Fig. 2). 1

The energization of relay 5 is now controlled from the terminus position.

In addition at the-tandem office (Fig. 3) through the ener 'ization of relay 14 a positive battery extends over the lower wire of the junction and is sent to the terminus oflice.

The circuit extends from positive battery on the lower wire to T141, R324, R292, T265, wiper and bank contact 1 of the finder R1, lower wire of the junction to the terminus oifice (Fig. 4), winding of the cuit: earth, T31, T92, R131, T101, interrupter spring and through the winding of the motor magnet of the finder RC1, to battery.

The arrival of the finder on the bank contact associated with the calling subscriber closes a circuit from earth, the two windings in parallel of relay C, TA2, bank contact and wipers of bank T1, T102, and battery through the winding of relay 13.

The operation of relay 13 opens the circuit at 131, of the motor magnet, at 132 it opens a circuit of relay 9, which releases and removes at T91 the battery from the upper wire of the junction.

In addition, relay C energizes and holds up in series with relay 13 from earth, windings of relay C in series, TCl, bank contact and wiper, etc.

At C3 and C4 the energization and holding circuits of the calling relay A are opened.

The removal of battery from the upper wire of the junction causes as described above the cut-off of the calling current. Alternating calling current is impressed on the upper wire of the circuit from the manual position as previously described, extends via R63, R91, alternating current relay 5, and earth through condenser G5 which causes the energization of relay 8 at T51.

By the operation of the latter a circuit is closed from earth, T31, T81, lower winding of relay 12, to battery.

Relay 12 holds up from battery, upper winding of said relay T121, T31, to earth.

The calling current is then sent to the subscribers bell over the circuit: upper wire of the junction, T82, H'2 (normal position of switch RC2), T125, bank and wiper +1 and contact associated with the subscriber in question, upper wire, bell, condenser, lower wire, bank contact, wiper and bank 1, T126, T83, and earth.

During the other period of the ringing, and if the subscriber unhooks, a circuit is closed from battery, left-hand winding of retard S2, RS3, T126, the previously described circuit via the receiver and secondary of the induction coil of the unhooked subscribers station, T125, H2, R82, upper winding of relay 9, earth.

Supervisory battery is sent from the upper line wire of the junction from battery, retard S1, R42, T91, upper wire of the junction, etc. The call is terminated and the supervisory lamp extinguished, as de scribed above.

The conversation currents pass through the two wires connected directly to the tandem office and through the condensers C1 and C8 at the terminus office.

Upon the'subscribers hanging up, relay 9 releases and removes the supervisory battery. Lamp LA lights at the manual position.

The removal of the plug causes by the removal of positive battery from the lower wire of the junction the return to its middle position of the polarized relays.

(a) Polarized relay 15 at the tandem office (Fig. 3) causes the release as described already.

(b) Polarized relay 16 at the terminus oiiice, Fig. 4, releases, which causes at 164 the release of relay 10, and at 162 the release of relay 3, which by opening contact 31 releases relay 12. Switch RC1 returns to normal over the circuit: earth, R31, bank and wiper 011, R101, interrupter of the rotary magnet RC1, winding of the magnet, to battery, and during rotation also over another circuit from earth, R71, R124, bank 001, etc. All the pieces of apparatus return thus to their initial positions.

I]. Subscriber called by the operator The operator puts a plug of the cord into the calling jack and so closes a circuit from battery, supervisory lamp LS, sleeve of the plug and the jack considered, H1, (if the counting switch is at zero), upper winding of relay 10, R23, to earth. This causes:

((0) At T106 the short circuiting of H1. (b) At T103 the lighting of the busy lamps L.O on the other positions.

(0) At "T102 a circult is closed from earth, interrupter spring of RC1, home contact of bank C, wiper W, T102, motor magnet, to battery. The latter operates by self interruption to move the wipers to position 1.

((5) At T104 a circuit is closed from negative battery and extended to the lower wire of the junction through the safety resistance, R61, T104, retard S, lower lefthand winding of the transformer, etc.

The operator next inserts her dialling plug in the corresponding jack and a circuit is closed from:

(a) Earth, through the contact C1 of the dial, ring of the plug, dialling jack and battery through the winding of relay 7, which operates.

(b) Interrupted earth via R22, sleeve of the dialling plug, dialling lamp LN, to battery, and the lamp flashes.

The operator can only dial during this signal.

The sending on the lower wire of the junction of a negative potential causes at the tandem ofiice, Fig.3, the operation of polarized relay 15 to its negative position,

which, therefore, closes contacts 151 and CPI 153, operatingat T151, relay 2. It is to be noted that if a subscriber at this time is calling at this o'lhce the signal will be removed from the upper wire of the junction by-the relea eof relay 9,'releasing from the opening of contact 21. Relay (Sis operated over the circuit: battery, through the wind ing ofsaid relay, 72/1, (normal position of RA) T153 to earth. Relay 27 operates through contact T23. Relay 6 holds up over the" circuit: battery, upper winding, T63, R84, T23, to earth.

The operation of relay 6 sends a circuit from battery through the safety resistance, T65, R322, winding of relay 31, to earth, via contacts H1 and H2 in series. circuit is only closed if the two switches R1 and R2'are in normal position.

The operation of relay 81 short circuits Lt-313 the contacts H1 and H2. A circuit isclosedfrom 'ba tery through the motor magnet R11, 262, T2311, R121, upper wine ing of relay 4 and earth, through it (normal position of switch It may be seen that relay 4 only energizes if the different pieces of apparatus in this circuit are in suitable positions.

The operation of the said relay causes the sending of the dialling signal over the. circuit: battery, upper winding of retard S1,

R132, T41, upper wire of the junction to the manual position, 2), R11, R41, relay 5, and earth.

Relay 2 operates over the circuit: earth,

-wiper Wz', position 1 of bank 13, T51, upper winding of relay 2, and battery through the safety resistance.

The opening of contact 22 extinguishes lamp LN.

The operator can now send the first digit. To this end, the dial is wound up so closing the circuit: earth, T172, (contact of the dial operated until its return to zero) ip of the plug, T21, lower windings of relays 2, 4, 6, to battery (through T71for relay 4). This causes:

(a) The holding up of relay 2.

(b) The operation of relay 4 which holds up via T42, upper winding, to battery. At T44 a circuit is closed from earth, T44, E82, wiper TV, position 1 of bank C, T102, motor magnet RC, and battery. The latter energizes and remains in the operated position.

(0) Relay 6 operates and negative battery is removed from the lower wire of the junction being replaced by positive battery. At the rural position, (Fig. relay 15 changes over to the positive position, contacts 151, 153, opening. Contacts 152, 154 close. Relay 2 remains held up via T152 (during the movement to the middle position. 152, and 151 open the said relay not releasing, being slow to release At T154 relay 13 energizes over the upper winding,

The said T61, T154, to earth. At R132 battery is removed from the upper wire and the latter the release of relay 7 a similar number of times causing the sending over the upper wire of a corresponding number of battery impulses over the circuit: battery, safety resistance, R71, T41, R11, upper wire of the junction, to the ruralposition (Fi 3), T41 T132 WlllCllIl of relavl to earth. a o v 7 lhe latter energizes a number of times corresponding to the digit set up on the dial, causing at T11 the advance of control switch RA.

In addition, as soon as the latter leaves its normal position, contact 7b is opened. Relay 4 remains held up via T45 and its lower winding, which is itself short circuited at R11 between each impulse, which causes the maintaining in the operative position of the relay during nnpluse train. As soon as the ten-point switch RA leaves its normal position, the following circuit is closed: eartii, bankl, 62, R31, R142, T311, R262, interrupter spring of the motor magnet of switch R1, to battery.

The said switch is set in automatic rotat-ion until it arrives on the contacts corresponding to the position of control switch RA. At this moment, the stepping circuit is as follows: earth, R323, J2 (in its normal position) J 1, bankcontact and control wire corresponding to the position of RA, bank 1, lower winding of relay 3, battery.

The operation of relay 3 causes at R31 the openingof the rotation circuit of R1, which is thus stopped 011 a position 'corre sponding to the digit sent, that is, a junction connected to another oilice or the line of a subscriber of the present office.

(.7) Call to a subscriber connected to the first 0773306 The digit sent is in this case ten corresponding to ten impulses. Switch RA is moved into the last position of banks 1, 1, 1-'.

Switch R1 being in a corresponding position, relay 3 is energized The train of impulses finished, relay 4 releases, owing toa prolonged short circuit of its lower Winding at R11. The following circuit is closed: earth, bank 1, T62, T81, R43, last position of the bank 1, interrupterspring of the motor magnet BA, to battery. The latter is set in automatic rotation and comes to the normal position of banks 2, 2, 2".

During this time relay 3 remains held up in'parallel with the motor magnet RA over ously energized) moves into position 2.

At the release of relay 6 positive is re-' relay returns to the negative position lay 13 releases.

tion, the relays 2, 4,

deenergization of its motor magnet previmoved from the lower wire of the junction and replaced at R61 by negative.

At the tandem ofiice (Fig. 3) polarized and relay 2 is held up via T151. Upon the opening of 154, relay 13 releases.

The ten-point switch having come to the initial positions of banks 2, 2, 2 as seen above, relay 4 energizes immediately upon the closing of IL in the circuit already described. Dialling battery is again sent over the upper wire over the circuit: battery,

upper winding of retard S1, B182, T41,

etc. The operations are repeated at the manual position as described above.

The dial is wound up. Positive is projected on the lower wire. The polarized relay passes to the positive position. Helay 13 operates. Tmpulses are transmitted to relay 1 over the lower wire of the junction. elay 4 remains operated via T45. Switch RA leaves its normal position, and stops on the position corresponding to the tens digit. In addition, the following circuit is closed: earth, bank 2 of the switch BA, T62, R31, R142, T311, R262, switch R1. The latter rotates automatically and stops by the opening of contact R31 (by the operation of relay 3) when it has arrived in position corresponding to the position of RA.

At the manual position (Fig. 2), the dial returns to normal, which causes:

(a) The movement of counting switch RC from position 2 to position 3.

(b) The disconnection of the upper wire of the junction from the impulsing circuit and its connection to relay 5.

(c) Flickering of the dialling lamp LN.

((Z) Finally, the replacing of positive battery on the lower wire by negative battery.

At the rural position 3), polarized relay 15 moves to its negative position. He- Relay 4 has remained normal from the time of the last impulse. If switch R1 is in the position corresponding to that of RA (representing the position of the tens digit chosen), the following circuit is closed: earth, bank 2 of switch RA, T62, T31, R43, bank 2, interrupter of rotary magnet RA. The latter comes to the normal position of banks 3, 3, 3", closing 7b, which causes the release of relay 4, and the sending stopped at the of dialling battery on the upper wire of the junction.

In the case where the equipment is only provided for fifty subscribers (example chosen in Fig. 3) five tens only are used, and if by error switch RA is positioned on a position corresponding to an unused ten the system is locked up. The locking circuit is closed on the unused positions 59. On these positions the stopping of the rotation of switch R1 is caused by operation of relay 3 (opening of R31), which finds an earth on bank 2 of switch RA.

The concluding of the impulse train causes the release of relay 4. A circuit is closed from earth, bank 2", T62, T31, B43, bank 2 on positions 5, 6, 7, 8, or 9, T131, and lower winding of relay 13. The latter remains held up and by the opening of contact R132, dialling battery is prevented from being reset over the upper released and the stoppmg relay 3 energized, the setting in automatic rotation of switch RA is assured by the following circuits:

(a) Positions 1, 2, 3, 4 T31, R43, bank and contacts in question of bank 2,

motor magnet RA, which operates by self interruption.

(Z2) Positions 5, 6, 7, S, 9 "31,

R43, bank contact in question, bank 2', R131, and motor magnet RA set in self-interrupted operation. It the switch is tenth position corresponding to digit 0 the rotation is resumed directly.

In supposing the chosen digit suitable, as we have seen above, the projecting of dialling potential on the upper wire permits by the extinction of the dialling lamp the sending of the third digit corresponding to units. The operations are identical to those already described, the following being a summary:

The dial is operated, positive battery is projected over the lower wire, relay 13 operates at the rural position (Fig. 3) through the movement of the polarized relay to its positive position.

Impulses are sent over the upper wire.

Switch RA rotates in accordance with the digit chosen, and switch R1 consequently rotates on to the line in question.

Relay 3 operates, relay 4 releases. A circuit is closed from earth, bank 3 of switch RA, T62, T31, R43, bank 3, winding of relay 11, R121, T311, R262, and battery through. the motor magnet R1. The latter does not energize in series with relay 11, but relay 11 energizes and closes at T112 a circuit and holds up for relay 9 over earth,

T112, lower winding of relay 9, to battery.

Relay9 energizes.

The dia-lreturns to normal position, causing the release of relay 13. By'the movement of the polarized relay from the positive to the negative position, a circuit is closed via S1, T91, R132, R41, upper wire of the manual position, where the operations succeed one another in the following manner:

Upon the return-to normal oi the dial the counting switch RC leaves position 3 and moves to position 4. By the removal of wiper 2 from position 3 of bank A, the circuit of the slow-to-release relay 3 is opened, battery being placed at this moment on the upper wire of the junction. he said relay remains held up at T52 by the operation of relay 5.

(a) Case where subscriber is free.

Atthe tandem oliice (Fig. 3) a circuit is closed from earth, T111, R131, T312, lower and upper windings of relay 26 in series, wiper andbank contact T1 of switch R1, winding of relayC of subscriber in question, to battery. These two relays energize in series and hold up over the circuit: T 71, T261,'lower winding of relay 26, winding of C, to battery.

The operation of relay 26 causes at 262 the opening of the energizing circuit of relay 11. Relay 11 releases and opens the circuit of relay 9,'which also releases, and battery is removed from the upper wire.

(5) Case where the subscriber is engaged.

(He is engaged through the medium of another connector).

In this case relay 26 (two windings in series) does not energize, being shunted by the lower winding of an identical relay of the finder connector held up by the. subscriber. By this means relay 11'is maintained held up, 9 is also held up, and battery is maintained on the lower wire.

At the manual office (Fig. 2), the switches are in the position indicated above. A circuit is closed from interrupted earth, position l of bank B, wiper VVl, T51, upper winding of relay 2, and battery through the safety resistance.

Relay 2 operating intermittently, at its contact 23 causes the unshort-circuiting of the lower winding of relay 10. The supervisory lamp LS is thus caused to flash.

The operator advised of the busycondition of the subscriber, withdraws the plug. The switches always return to the normal position as we shallsee.

If the communication is urgent, the operator can enter into conversation with the busy subscriber in the following manner:

The listening key of the cord used is depressed, then by the operation of the busy subscribers listening key (individual to the operators position) an earth is sent in parallel on the two conversation wires, the two right-hand lines in parallel of the transformer, R81, upper winding of relay 6, to battery. The operation of relayb causes the changing over of battery on the lower wire of the junction to positive from 1re ative as long as the forced listening key is depressed.

At the rural position (Fig. 3), the movement of the polarized relay 15 to the positive position operates relay l3. Relay 5 operates over the circuit: earth, T111, T131, winding of relay 5, to battery.

The conversation circuit is established from upper wire of the junction, condenser C1, condenser C5, T51, T31 1, wiper and bank contact +1 of switch R1, upper wire of the subscribers line, and lower wire of the junction, condenser-C2, R82, R141, condenser CG, T52, T314, wiper, and bank contact -1 of switch R1, lower wire of the subscribers line.

The operator can warn him or" the urgency of the communication. He releases the prior communication by hanging up, to be automatically recalled by the circuit in question.

In all cases, the subscriber being or becoming free, battery is removed from the upper wire as described above. The call is cut off automatically at the manual position, Fig. 2. We get as already described, the release of relay 5 which at 51 opens the circuit of the interrupted earth, so releasing relay 2 (supervisory lamp LS gives a fixed glow).

Relay 3 releases by the opening of contact 52.

Relay l-operates intermittently via B31 in accordance with the interruptions for controlling calling current.

RC energizes via R32.

Periodic alternating current is projected on the upper wire or the junction. At the rural position (Fig. 3), alternating current relay 7 o eratgs and relay 8 operates via contact T? 1. The call is extended to the subscriber by theupper wire 01' the junction, ltll, T81, R141, R323, R291, T263, wiper and positive bank contact, upper conductor of the subscribers line, bell, condenser, lower conductor of the subscribers line, bank contact and negative wiper 1265,3292, R32 R141, T82, to earth.

In addition, at R84 the holding circuit of the upper winding of relay 6 is opened, he lower winding of this relay having been opened at 262, it releases. life get:

(a) Automatic rotation of RA over the circuit: earth, bank 3", R62, interrupter spring, rotary magnet RA and battery, via the home contact. In position 4 we get: earth, R64, home contact of bank 4', motor magnet of BA, to battery. Said switch moves to posit-ion 1, bank 4-, and a circuit is closed from earth, bank 1", R62, motor mag lower winding of relay 26, wiper The latter moves to the home position of bank 1, closing 7L1, hl. 71/1. Relay 6 energizes from earth, T153, hl, upper winding of said relay, to battery.

. (b) By the momentary opening of contact T relay 31 deenergizes, and by the opening of 313 its locking circuit to T65 is opened permanently (H1 of R1 being opened). .Vhen the called subscriber replies, relay 9 operates (/61 being closed) and following the same operation as previously described in chapter Reply to a Call, battery is sent via the upper wire of the junction.

At the manual position (Fig. 2), we get energization of 5, energization of 2, extinction of supervisory lamp LS, and at contact 32 the opening of the circuit of BC and its passing from position 4 to position 5.

The operator, being notified, can enter into the conversation with the subscriber as already described.

UaZZ to a subscriber attached to the terminus 077506 net BA, to battery.

Let us return to the stage of the operation corresponding to the finish of the sending of the first digit supposing the latter corresponds to a junction (in the example chosen position 6, 7, 8, and 9 of bank 1, Fig. 3), the switch R1 remains in this case locked up in this position until the time of a call or until the calling plug is withdrawn. The following circuits are closed: earth,

bank 1, T62, T31, or 9 of bank 1 as chosen, lower relay 14, to battery.

Relay 14 energizes and holds up from battery in series with resistance R1 via its upper winding T143, T23, to earth. A circuit is also closed from earth, T143, R131, T312, the two windings in series of relay 26, wiper and bank contact T1 of switch R1, winding of cut-oft relay C of the junction being considered, to battery.

Relay 26 energizes in series C, and holds up R43, position 6, 7, '8, winding of with relay and bank contact T1, C to battery.

At this time negative battery existing on the lower wire of the junction is extended to the terminus ofice over the circuit: T141, R324, R292, T265, wiper and negative bank contact of switch R1, R1, lower wire of the junction and polarized relay 16 to the terminus oiiice (Fig. 4). Relay 16 energizes to its negative position, closing its contacts 161 and 163. A circuit is closed at T161, to energize relay 3which closes its contact T31.

At T163, relay 2 energizes and holds up over the circuit T24, T31, to earth. It closes 1 the following circuit: earth, T23, H2, (norirom earth, T271, T261,

mal position of switch RC2) H1 (normal position of RC1), lower winding of relay 9, to battery. The latter operates and closes the following circuit: battery, retard S1, R42, T91, R63, upper wire of the junction to the tandem position, Fig. 3, bank contact and positive wiper of switch R1, T263, R291, R323, T141, R41, and upper wire of the junction to the manual position. This causes the extinction of the dialling lamp LN.

The operator is now able to send the second digit. In the case where the junction is not free, relay 26 not being able to operate in parallel with the lower winding of a similar test relay, the circuits indicated above remain open at contacts 263 and 265.

The operator notified of this condition by the flickering of the dialling lamp LN can enter by force into the conversation as described above (busy condition of a subscriber to the tandem oflice) earth being extended to the circuit of relay 5 at T143.

In reconsidering the case of a free junction, the operator sends the tens digit, the terminus oiiice being in the example chosen equipped for twenty subscribers, the said di it being 0 or 1 (ten impulses or one impulse). A special arrangement at the terminus oiiice permits without the interposition of auxiliary rotary switches finds subscribers in accordance with normal numerical order.

Upon the winding up or the dial, positive instead oi negative is projected on the lower 'wire of the junction, and at the tandem oiiice (Fig. 3), this causes relay 15 to move to its positive position. Relay 13 energizes and opens at contact 132 the circuit of the upper winding to earth of relay 7 via the upper wire before the transmission of the impulses. It may be noted at this point that the upper dialling wire is directly connected to the terminus office without any shunt.

t the terminus ofiice (Fig. 4), the polarized relay 16 passes from its negative to its positive position, opening at contact 161 the circuit of relay 3, immediately reclosed at contact T162. This relay being slow to release remains operated during this changeover of position. 7

1 t T164 a circuit is closed from earth, T164, T22, winding of relay 6, to battery. The latter energizes and opens at R63 the circuit of the supervisory battery and connects the upper wire of the junction to reay 1 at contact T63 which is above to receive the impulse of the tens digit sent from the manual position.

(a) The digit sent is 1.

Relay 1 energizes in response to the impulse and closes at contact 11 the following circuit: earth, T11, R151, left-hand winding of relay 15, to battery. The latter energizes on its left-hand winding alone and closes contact T151.

the opening of contact 11, a circuit osed from battery, left-hand winding of 15 in series with right-hand winding i. :aine relay, T151, B81, T31, to earth. The cncrgization of the right-hand winding of the said relay causes the closing of contacts 151, 152, and 153.

The impulse train being terminated, the polarized relay 16 returns to its negative position, causing the deenergization of relay 6. A circuit is closed from earth, T31, T92, (RC1 being in its initial position) R111, R62, T152, lower winding of relay 7, to battery. The latter holds up over the circuit T152, T72, T31, to earth.

Dialling battery is projected on the upper wire at R63.

((3) The digit sent is O (ten impulses).

As before, the first impulse causes the energization of relay 15 via its two windings.

The following nine impulses are sent to the switch RC1 over the circuit: earth, T11, T151, 122, motor magnet RC1, to battery. When the switch arrives at position 9, a cir cult is closed from earth, R71, R124, contacts 9 and 10 of bank a l, R101, motor magnet 161 which is in seltintorrupted operation, to battery. The latter moves over the two marked positions by automatic rotation and comes to rest in a position corresponding to the digit 10, closing Hl.

The impulse train being terminated, relay (3 releases through the movement of polarized relay 16 to its negative position.

A circuit is closed from earth, T23, H2, Hl, T153, lower winding of relay 9, to battery. Relay 9 operates. At T91 dialling battery is extended to the upper wire of the junction.

It may be seen from the preceding that the said battery can only be sent it the switch in question is. in the home position, corresponding to the tens digit chosen (closing of H1 or Hl).

The operator then sends the units digit.

This causes the movement of switch RC1 to the corresponding position over the cir cuit: earth, T11, T151, R122, motor magnet RG1, to battery.

It the switch is rotated to one of the two subscribers corresponding to the numbers 19 and 10 in moving over the contacts corresponding to $1, the automatic rotation circuit previously described is opened at R71, relay 7 being energized. In addition, the switch having arrived in this position, the following circuit is closed: battery, winding of RC1, interrupter spring, R101, bank contact 9 or 0 of bank 021, R124, T71, upper winding of relay 7, to earth via T31. Relay 7 is thus maintained operated and will remain held up if the circuit of its lower winding is opened. The third impulse train having terminated, a negative battery exists on the lower wire of the junction and no battery exists on the upper wire. The call is cut oil at the manual position.

At the tandem oflice (Big. 3), the energization oi relays 7 and 8 causes the release of relay 6, as for a call to a tandem oilice subscriber. This insures the automatic rotation of switch RA, through the medium of banks 1, 2", 3", 42", and R62 and the normal positions 2, 3, 1, R6 1. The latter then returns to the home position of banks 1, 1, 1, closing the contacts 721, iil, 7W1. Relay 6 energizes via contact 71/1. (2) During the openin of contact T65, relay 31 has remained released as we have previously seen.

In addition, relay 14 being always energized, theclosure of contacts 81 and 82 is without client, their circuits being opened at R141 and R141.

The calling current goes direct to the terminus position by the upper wire. A circuit is closed 1), from R63, R91, alternating current relay 5, to earth, via con denser C5. Relay 8 operates via T51. At {81 the energizing circuit of relay 15 is opened. It releases and opens contact T152, so opening the energizing circuit of the lower winding of relay 7 which falls back, excepting when the switch RC1 is in positions 19 and 10. Tn this case relay 7 remains held up by its upper winding as described above.

At T81, relay 12 is energized over the circuit: T31, T81, lower winding of relay 12, to battery. Relay 12 holds up over the circuit: battery via its upper winding, T121, T31, to earth (the latter opens in the present case at R124, the holding circuit of relay 7). At this moment, the call is extended to the subscriber over the circuit, upper wire of the junctions, R63, T82, H2, (normal position RC2), T125, bank +1 and positive bank contact of the chosen subscriber, upper wire of the subscribers line, bell, condenser, lower wire of the subscribers line, negative bank contact, ban -1, T126, T83, to earth.

The chosen subscribers calling relay A energizes through its upper winding, it being inserted in the line. By the closing of contact TA2, relay C energizes in series with relay 13 and opens at C4 the circuit of the calling relay A, relay C then remaining energized via T01.

The following operations are then identical with those described above in Chapter I Call by a rural subscriber.

[I]. Local 001mnum catim2-sthe description cont inning from the time of the reply of the subscriber The operations being the same as described in Section T, the apparatus is in the following positions: Fig. 2, plug of a cord is inserted in answering jack.

Supervisory lamp LS is extinguished (the calling subscriber having answered the recall signal). Relays 3, 5, 2, 8, 10' are energized,

switch RC is in position 5, positive battery is on the upper wire of the junction. The operator having taken the requirements of the subscriber inserts the dialling plug in the corresponding jack and this causes the energization of relay 7. The holding circuit of relay 8 is opened at R71. The latter opens at T81 the energizing circuit or" relay 6-which falls back and so extends negative battery to the lower wire of the junction.

At the tandem oilice (Fig. 3), polarized relay 15 moves to its negative position. Relay 2 remains energized via T151. The circuit of relay 12 is opened at T15& and it opens at T124 the circuit of relay 31, which falls back.

At T153 relay 6, which is slow to operate, is energized by its upper winding, via h'l. It holds up over the circuit: T63, R84, T23, to earth.

At the manual position (Fig. 2), dialling lamp LN being extinguished the operator winds up her dial and a circuit is closed by the closing of the dial contact C2 to energize relay at in series with T71. The said relay holds up at Tl2. Relay 6 also holds up and at T61 sends positive battery to the lower wire of the junction.

This causes at the tandem the energization of relay 13 polarized relay moving to its tion).

The following circuit is closedzbattery, via the safety resistance, T65, R322, T264, R811, winding of relay 22, T1233 to earth.

Relay 2 energizes and holds up via con tact T221. Belay l energizes via T133.

(1) Case where the calling sul scriber is in the tandem oflice.

The first impulse train received by relay 1 (Fig. 3) causes the rotation of switch RA. into the position determined by the digit chosen.

At the closing of bank 1", a circuit is closed from earth, bank 1, T 62, 1331, R142, T222, 3242, battery via motor magnet R2, which operates by self interruption.

Switch R2, leaving its normal position, closes the following circuit: earth, x2, battery via the winding of relay 29, which energizes. The latter opens circuitsof supervision of S1, and also of relay '9 of the calling subscriber at R291 and R292. The subscribers line being reconnected at T291 and T292, on to av similar arrangement consti- ..r*.' mace, rig. 3, rise (the positive posituted by battery ln'ough the upper winding of retard S2, T292, lower wire of the subscribers substation, upper wire T291, relay 25, to earth. The latter energizes. The calling subscriber remaining in the main circuit via condensers C3 and 6-1.

The dialling operations follow next b using this time switch R2, by a met ium e f relay 22 in the same manner as described in Section II (dialling a subscriber), the latter being connected toa tandem office or a terminus otlice.

(2) Case where the calling subscriber is connected to a terminus ottice.

The beginning of the operations is the same as those described above. Relay (5 (Fig. 4) energizes and holds up.

In the case considered, relay 1% being energized remains held up via T143 and T23, to earth.

The inversion of battery on the upper wire has been received at the terminus otlice, Fig. l, on relay 16, and this causes the energization of relay 2 which holds up at T24. Relay 10 deenergizes.

The conditions at this ofiice are then as follows:

Switch RC1 is held by the calling subscriber, relay G of the said subseribers line is energized, relays 12, 9, 2, 3, are energized, relay 16 is in the negative position. All the other relays are normal.

Upon the winding up of the dial preceding the first digit train, relay 15 (Fig. 3) moves to its positive position. Relays 13, and energizes as already described.

Upon the energization o1": relay l, the circuit the upper wire of the junction is opened at and is connected. to relay 1 at T41. .lt wi that the first impulse train will only be received on relay T at the tandem ollice.

Three eistinct cases then present themselves:

(a) The called subscriber is connected to the tandem otlice.

(b) The called subscriber is connected to a terminus otlice diilerent from that of the calling subscriber.

(c) The called the same terminus oiiice subscriber.

In the two first cases a and b the local connection may be established through the medium of switches R1 and R2 of the tandem ofilce.

subscriber is connected to as the calling In the third case (a) only switches RC1 and Hi2 of the terminus otiice in question will beused.

(a) The subscriber is connected to the tandem oi'tice.

A number received on switch RA has caused the movement of this switch on to the stopping wire corresponding to the arrangement ot the subscribers in the ollicc, but, contrary to the operation previously described, switch R2 has not been set in rotation through the closing of bank 1, the circuit previously described being obtained at R142 (1d being energized).

At the end of the impulses, relay 4: deenergizes and a circuit is closed from: earth, bank 1, T62, B31, T142, R 12, resistance R1, to bat cry, which causes relay 1%- to be short circuited. This relay releases. The

rotation circuit or" R2 is closed at R142. The latter starts oil in rotation and is stopped at the desired position by the energization o1 relay 3 in the following circuit: earth, R323, J2, via the bank of switch R2, control wire considered etc.

Switch R2 leaving its normal position cuts of? the control earth of wiper J1 at J 2 and at 02 energizes relay 29.

The apparatus at the terminus oflice is then held up from the tandem oflice in operated position over the circuit: battery, upper winding of retard S2, T292, T262, etc.

Polarized relay 16 of the terminus position (Fig. 4) is at its negative position.

In addition, the supervisory battery (as long as the calling subscriber remains on the line) is extended by the upper wire of the junction to relay 25 of the tandem oliice (Fig. 3) over the circuit: T263, T291, winding of relay 25, to earth (the subscriber remains in circuit via the condensers C3 and C4).

The operations follow at the tandem ofiice as already described in Chapter III.

(7)) The called subscriber is connected to a terminus oiiice, different from that of the callin subscriber.

The number received on switch RA, Fig. 3, has caused the movement of this switch until the stopping wire corresponding to the junction to be used is reached.

As previously, the switch R2 is not set in rotation until the conclusion of the impulse train.

Relay 4 releases and short circuits the upper winding of relay 14, which releases.

Switch E2 is set in operation, and the circuit of the calling subscriber is moved to the local connection device at T291, and T292 by the operation of relay 29.

The stopping on the junction considered is brought about by the operation of relay A circuit is then closed from earth, bank, 1", T62, T31, R43, bank 1, bank contact corresponding to a junction, winding of relay 14, to battery. The latter energizes and when the dial returns to normal (15, in the negative position, 13 released) causes the energization of relay 24 (if the junction considered is free) over the circuit: earth, T143, R131, T223, the two windings in series of relay 24, wiper T2, bank contact T, relay C of the chosen junction to battery. two relays energize in series and hold up at T241 to the earth at T271.

The main circuit is from that time directly connected to the junction of the calling subscribers terminus oiiice, over the circuit: upper wire R41, T141, R323, T242, wiper and bank contact +2, etc., lower wires T141, 3324, T245, wiper and bani:

These contact 2, etc.

The operations follow next at the terminus otlce as previously described in Sec tion H, the. only differ nce being at the manual posi on, 2, where the positions of the counting switch RC1 are successively 5, 6, 7, 8, and 9, respectively, lntical to the positions 1, 2, 3, 4, and 5.

In the case of the, two examples already mentioned, and at the end of the operations, the call being cut off, alternating current relay 7 operates at the tandem oflice, Fig.3, and also relay 8. At contact 84, the holding circuit of relay 6 is opened, which causes the return to zero of switch RA, the latter closing its contacts 7L1, 72/1, /L"1. Relay 6 reenergizes at hl. By the opening of T65, relay 22 releases and does not reenergize upon the reclosing of contact T65, its circuit being opened at T221 and T133. If the called subscriber replies the o aerator is notified (as previously describedh by the cxtinctionot supervisory lamp LS. The two subscribers calling and called converse through the medium of condensers C3 and C4.

The operator can release the operation of the circuit not utilized by the local connection. To this end, she withdraws the plugs lialling plug), the potential of occupation (negative) is removed from the lower wire of the main circuit, and this causes the release of polarized relay 15 at the tandem ofiice (Fig.

A circuit is then closed from earth, R221, T224, lower winding of relay 32, R322, Wind ing of relay 2, to battery (this circuit prepared at the time of the call of the second subscriber only causes the energization of relay 32 upon the opening of the short circuit at T151). The latter energizes and holds up at T321 to battery via resistance R2. At T324 battery is sent on the lower wire either of the subscribers if he is connected to a tandem oifice or of a junction if he is connected to a terminus otiice. In this case this battery replaces that which is about to be removed from the manual position and maintains through the medium of polarized relay 16, Fig. 4, the terminus oiiice apparatus in the operated position, the momentary removal of the said battery not having caused the release owing to slow release relay 3.

In both cases, there will be a battery on the upper wire as long as the called subscriber remains on the line. T323 is sent via relay 23 to earth. Relay 23 energizes. The holding circuit is then closed from earth, T231, T251, relay 27, battery, the said relay (slow to release) having just had its energizing circuit opened at 3.321.

In addition, at T322 the switch-taking circuit is transferred to relay 28.

At 323 the control earth is removed from J 2 and is transferred to J 3.

This battery at i Polarized relay 15 releases (returns to its middle position) and the restoration to normal of the apparatus associated with'the principal circuit, is brought about and this includes relays 1-15 of switch RA.

The principal or tandem ofiice circuit can then deal with either rural-manual or manual-rural calls through the meoium of switch R3 in the same fashion aspreviously described in Chapters I and II with the use of switch R1. Relay 31 being replaced in the description by relay 28 as long as relay 32 remains energized.

When the conversation between the two local subscribers is finished, they hang up and this causes the release of the apparatus used for the establishment of the said connection.

Upon the hanging up of either one of the two subscribers, supervisory battery is removed from the upper wire of the junction either directly or through the medium of relay 9, Fig. 4. It the subscriber in question is connected to a terminus ofiice, this causes at the tandem oilice the release of corresponding relays 23 'or 25, or both. These at 231 or 251 open the energizing circuit of 27 which releases some time afterwards (the latter being made slow to release in order to avoid a momentary opening of the circuit indicated above which would cause the release).

By the opening of T271, the circuit of relays 24 and 26 is opened, these release and open the lines respectively at 263, 265, and 242, 245, which causes the removal of battery (through retard S2) from the lower wires. This causes in the present case the release of the terminus ofiice used through the deenergization of polarized relay 16 (Fig. 4).

At tandem office the release of relay 26 causes also the resetting to normal of switch R1 over the circuit: earth, 001, R311, R262, motor magnet R1, to battery.

The release of relay 25% causes the resetting to zero of switch R2 over the circuit: earth, :02, B222, R2 12, motor magnet R2, to bat tery. Upon the opening of $2 relay 29 releases.

Finally, at 24s, the energizing circuit of the lower winding of relay 32 is opened. Ti the main circuit is occupied at this time (using the switch relay 32 remains energized over the circuit: battery, upper winding, T 321, T 23, to earth, maintaining thus the switched condition of the connection on B3. The circuit having become released, the said relay releases and reprepares the switching on to switch R1 at R323, R322, R321, R323, R324.

0) The called subscriber is connected to the same terminus ollice as the calling subscriber.

Let us consider the functioning of the arrangemcnt as explained at the beginning of the uses ((1,) or (7)).

The first digit in this case received on switch RA oi ahe tandem oliice, Fig. 3, has caused the rotation of switch E1 on to the control wire corresponding tothe position occupied by switch RA. A circuit is closed from earth, R323, J 2 on its normal position, J 1, control wire considered, bank 1 ol switch RA, and battery through the lower winding of relay 3 which energizes. The latter opens at R31 the short circuit to relay 1%, which in this case remains held up. Owing to this fact, switch R2 will not'be put in ope 'ation, its rotation circuit remaining open at R142.

At the end of the first impulse train, relay t releases and will not be reenergized during th two other trains, its circuit being opened at 7:.1. At R41 the main circuit again directly connected to the calling terminus ofiice which is about to receive the two following impulse trains, during the course of which in the tandem ollice, relay 18 (through the medium of relay 15) will open at T132 the circuit of relay 7 to earth.

At the terminus position, 1g. i, we have he following: relay 9 being held operated :hrongh the answering oi the calling subiber and also the sending of dialling battery to the manual position immediately upon the completion of the previously described circuit to the tandem oilice.

The operator w'nds up the dial, polarizes relay 16 moves to its positive position. Helay (3 energizes and connects at T63 relay 1 to the upper wire of the junction.

The impulses sent are received on the said relay which as previously described correspond to the digits 1 or 0 (one or ten impulses). This causes the energization of relay 15 and the maintaining in its initial position of switch RC2, or its return to the beginning of the second. ten over the circuit: batten T11, T151, (af er the first impulse) T122, R142, motor magnet RC2 to battery, T11, T151, (after the first impulse) T122, R142, motor magnet EC to battery. The latter thus moves automatically to the normal position of the second ten over the circuit: earth, T71, R145, positions 9 and 0 of the first ten, bani: a2, and battery via the motor magnet which is in self-interrupted operation.

The impulse train having finished, relay 16 returns to its negative position, relay 6 releases, diailing battery is sent over the upper wire, relay 9 being held up, in the case (beginning of first ten) by the barging up of the calling subscriber as previously, in the second case (beginning of the second ten) over the circuit: earth, T23, H2, H2 T2, T1513, lower winding of relay 9 to battery; the upper winding of the said relay being disconnected from the upper wire of the calling subscriber at 1:12 as soon as switch RC2 leaves its normal posi tion in the first ten. I

In addition and in both ca es, energizes over a circuit: earth, T31, 1J2, 111, R62, R152, lower winding of relay 7 to battery.

Relay 7 holds up over the same winding T152, T72, and earth at T31. This i 1- thattime by the opening of t l '1 switch RC2 to rotate s 9 {0 pos of the first ten, without being automatically taken back to the home position of the fol lowing ten.

The units digit is then sent in the usual manner, which causes the rotation in the chosen ten of switch RC2 on to the called subscriber.

The call t in th usual manner, which causes me enegization 0t relays 5 and 6 (the call not to the calli W" subscriber-his circuit being opened at 1T2 and R82). The en'ergization of relay 8 causes also T31 the onergization of relay 1&- through lower winding unshort-circuited by the opening of H2. It holds up via T1 11, R61, T31, to earth.

The call is at this time extended towards the called subscriber as already described by the closing of T1 14- and T1 16. Upon taking off the receiver by the latter, relay 9 energizes over thv circuit: earth, upper winding of 9, R82, This, substation T1416, R84, to battery through left-hand winding of retard S2. Supervisory battery is sent on the upper wire of the junction. he calling finished, the operator is notified or the reply 01"? the subscriber and can release by withdrawing the plug.

The two subscribers are in communication via the condensers C2 and C4.

Upon energization of relay 1 1, relay 11 is put in circuit at T143 on to the calling subscriber instead of relay 9 which transferred to the called subscriber. The two subscribers being unhooked. these two r lays are energized.

When the operator releases, relay 16 comes to middle position, and a circuit is closed from T31, T92, T111, lower winding of relay 41, to battery througl'i the winding of relav 3. i

Relay 4 energizes and holds up through its upper winding at T41. At T413 the lower winding is next short circuited, finally by the opening of 42 battery is removed from the upper wire or the junction.

Upon either subscribe hanging up, the switches are re nod to normal, T92 or T111 opens. Relay 3 releases slowly, the holding circuits of relay- 2, 1, 12 and 14 are opened at T31, switch RC1 returns to its home position via R31 and R71 as already described, and switch RC2 via R23 and E71.

. If during the time when a local connection is established as above, the junction is taken for the establishing of a manual communication through the medium of switches R1, R2, or 01 the tandem of free, the following takes place:

The operator after sending the first digit receives the busy signal through the flickering oi" the dialling lamp (battery being removed from the upper wire of the junction at the terminus ollice at R42). The operator by the operation of her listening key enters into the conversation directly with the subscribers in the local connection and asks them to release. It is possible, in cases of extreme urgency, to force the release 01 a local connector by the operation of her forced listening key which causes as previously described the movement from the negative to the positive position of polarized relay 16.

Relay 6 energizes, and at 61 opens the holding circuit or" relay 14. Relay 9 deenergizes. Upon the withdrawal of the plug, the switches return to normal as described above.

The various preceding descriptions relating to the putting into communication of two local subscribers following upon the call of a calling subscriber can equally well be applied to the case where both subscribers are dialled. 1

The first stage is described in Section II (call of a subscriber) then without further operations being included, the dialing of the second subscriber takes place as described above in Section III.

In addition, at the tandem otlice, Fig. 3, an arrangement for listening and for releasing the local connection is provided.

The operator dials on the principal circuit corresponding to the local engaged connector a digit which causes as described al ready the movement of switch E3 on to the listening circuit. Relay 21 energizes in the same manner as cut-oil relays C and C. Listeningin, and the conversation is then dependent upon condensers C7 and C8.

The operator can advise the subscribers to hang up and can, in cases of extreme ur-, gene; release from the oflice by the operation of her forced listening key the subscribers in the connection.

To this end, the following takes place: Relay 15 moves to its positive position. Relay 13 energizes. Relay 23 is short circuited over the circuit T211, T133, to earth. The latter releases, causing the deenergizaion of relay 2?, which causes the switches used in the local connection to return to normal. The operator can after plugging use switches R1 and R2 to establish other connections.

What is claimed is:

1. In a telephone system, two offices, calling lines and called lines in one oflice, a 

